WO2018116586A1 - Catalyseur sur support métal - Google Patents

Catalyseur sur support métal Download PDF

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WO2018116586A1
WO2018116586A1 PCT/JP2017/036764 JP2017036764W WO2018116586A1 WO 2018116586 A1 WO2018116586 A1 WO 2018116586A1 JP 2017036764 W JP2017036764 W JP 2017036764W WO 2018116586 A1 WO2018116586 A1 WO 2018116586A1
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metal
carbon
supported catalyst
platinum group
atoms
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Japanese (ja)
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亮 釜井
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
    • B01J31/16—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes
    • B01J31/22—Organic complexes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/92—Metals of platinum group
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/15—X-ray diffraction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2235/00—Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
    • B01J2235/30—Scanning electron microscopy; Transmission electron microscopy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present application relates to a metal-supported catalyst supporting a metal.
  • Platinum group elements exhibit high catalytic activity for various chemical reactions and are widely used industrially and commercially as catalysts.
  • fuel cells, hydrogen generators by electrolysis of water, and the like have attracted attention as new energy utilization devices.
  • the fuel cell uses an oxygen reduction reaction and a hydrogen oxidation reaction
  • the hydrogen generator uses a hydrogen generation reaction.
  • a platinum group element is suitably used as a catalyst. Therefore, the need for platinum group elements is expected to increase.
  • platinum group elements are generally rare and expensive, and the price is unstable. From the viewpoint of saving resources, securing availability, and reducing costs, it is strongly desired to reduce the amount of platinum group elements used.
  • Patent Document 1 As a method of reducing the amount of platinum group element used, as disclosed in Patent Document 1, it has been proposed to reduce the size of platinum group element particles carried on a carrier. In addition, as disclosed in Patent Document 2, it has also been proposed to support metal cluster nanoparticles containing a platinum group element on a carrier.
  • One non-limiting exemplary embodiment of the present application provides a metal-supported catalyst with a low proportion of platinum group elements and high catalytic activity.
  • the metal-supported catalyst according to the first aspect of the present invention contains a platinum group metal atom and a carbon atom.
  • the mass ratio of platinum group metal atoms to carbon atoms measured by X-ray photoelectron spectroscopy is W, and in the image observed with a high-resolution transmission electron microscope, the projected area ratio of platinum group metal atoms to carbon atoms is When S R , S R / W is 2.0 or more and 4.0 or less.
  • the metal-supported catalyst according to the second aspect of the present invention includes a porous carbon-based material containing carbon atoms, a surface of the porous carbon-based material, a particle diameter of 0.5 nm to 15 nm, platinum, And metal particles containing a group metal atom.
  • the mass ratio of platinum group metal atoms to carbon atoms measured by X-ray photoelectron spectroscopy is W, and in the image observed with a high-resolution transmission electron microscope, the projected area ratio of platinum group metal atoms to carbon atoms is When S R , S R / W is 2.0 or more and 4.0 or less.
  • FIG. 1A to 1D show examples of compounds containing at least one of a nitrogen atom and a sulfur atom.
  • (E) to (h) in FIG. 1B show examples of compounds containing at least one of a nitrogen atom and a sulfur atom.
  • FIG. 1C (i) shows an example of a compound containing at least one of a nitrogen atom and a sulfur atom.
  • FIG. 2 is a schematic view showing an example of a fuel cell according to an embodiment of the present invention.
  • FIG. 3 is a photograph showing the results of observation of the metal-supported catalyst of Example 1 with a transmission electron microscope.
  • FIG. 4 is a photograph showing the results of observation of the metal-supported catalyst of Example 2 with a transmission electron microscope.
  • FIG. 5 is a photograph showing the results of observation of the metal-supported catalyst of Comparative Example 1 with a transmission electron microscope.
  • FIG. 6 is a photograph showing the result of observation of the metal-supported catalyst of Comparative Example 2 with a transmission electron microscope.
  • platinum particles with a diameter of 3 nm correspond to a surface exposure rate of about 30%.
  • the diameters of the supported nanoparticles are distributed, even if the average value is 3 nm in diameter, the average surface exposure rate is almost less than 30%. Therefore, especially when considering application as an oxygen reduction catalyst, there is a limit in improving the catalytic activity per unit weight of the platinum group element simply by making the metal particles small.
  • the present disclosure provides a metal-supported catalyst having a higher surface exposure rate than before and an electrode using the metal-supported catalyst without reducing the high catalytic activity of the platinum group element.
  • the inventor of the present application has conducted intensive research on a method for realizing a catalyst having a high surface exposure rate of a platinum group element without causing a decrease in catalytic activity of the platinum group element, in particular, oxygen reduction activity. .
  • the inventors have conceived that the shape of the platinum group element particles to be supported is controlled and the surface exposure rate is increased by appropriately designing the formation process of the platinum group element nanoparticles.
  • the outline of the metal-supported catalyst of the present disclosure is as follows.
  • the metal-supported catalyst according to an embodiment of the present disclosure includes a platinum group metal atom and a carbon atom.
  • the mass ratio of platinum group metal atoms to carbon atoms measured by X-ray photoelectron spectroscopy is W, and the projected area ratio of platinum group metal atoms to carbon atoms in an image observed with a high-resolution transmission electron microscope When S is S R , S R / W is 2.0 or more and 4.0 or less.
  • a metal-supported catalyst according to another embodiment of the present disclosure includes a porous carbon-based material containing carbon atoms, a surface of the porous carbon-based material, a particle diameter of 0.5 nm to 15 nm, platinum, And metal particles containing a group metal atom.
  • the mass ratio of platinum group metal atoms to carbon atoms measured by X-ray photoelectron spectroscopy is W, and the projected area ratio of platinum group metal atoms to carbon atoms in an image observed with a high-resolution transmission electron microscope When S is S R , S R / W is 2.0 or more and 4.0 or less.
  • the platinum group metal atom may contain at least one selected from the group consisting of Ru, Rh, Pd, Os, Ir and Pt.
  • the platinum group metal atom may be Pt.
  • the metal-supported catalyst may further contain at least one of a nitrogen atom and a sulfur atom.
  • the metal-supported catalyst of the present disclosure includes a platinum group atom and a carbon atom.
  • the metal-supported catalyst includes a carbon-based material containing carbon atoms and metal particles containing platinum group atoms.
  • the carbon-based material functions as a carrier for metal particles.
  • the carbon-based material preferably has at least one selected from the group consisting of, for example, carbon black, graphene, graphite fine particles, carbon paper, carbon cloth, and carbon felt. From the viewpoint of more stably supporting metal atoms, the carbon-based material is preferably a porous carbon-based material containing carbon atoms.
  • the carbon-based material more preferably contains at least one of a nitrogen atom and a sulfur atom.
  • Nitrogen atoms and sulfur atoms may be doped in the carbon-based material.
  • a layer containing a compound having at least one of a nitrogen atom and a sulfur atom and having a thickness of several nm or less may be formed on the surface of the carbon-based material.
  • “dope” refers to a state in which carbon atoms in a bonded state by sp 2 hybrid orbital constituting carbon black are substituted with nitrogen atoms or sulfur atoms. Such a doped state can be confirmed, for example, by performing a Raman spectroscopic measurement.
  • the form of such a doped nitrogen atom or sulfur atom is not particularly limited. Moreover, when providing the layer containing the compound which has at least one of the nitrogen atom and sulfur atom of thickness of several nanometers or less, the layer may be formed over the whole surface of carbonaceous material, and only in part It may be formed.
  • the compound containing at least one of a nitrogen atom and a sulfur atom is preferably a material having a large molecular weight so that elimination from the carbon-based material is suppressed.
  • the molecular weight is preferably 1000 or more.
  • Such a compound containing at least one of a nitrogen atom and a sulfur atom may be, for example, an oligomer or a polymer having a repeating unit shown in (a) to (i) of FIGS. 1A, 1B and 1C.
  • the carbon-based material includes at least one of a nitrogen atom and a sulfur atom on the surface
  • a lone electron pair of the nitrogen atom or the sulfur atom becomes an ion of a platinum group element ( Coordinate to a cation).
  • the platinum group atoms can be held on the surface of the carbon-based material in an ion state of each platinum group element, not in an aggregated state.
  • the oligomer or polymer structure having the repeating unit shown in (a) to (i) of FIGS. 1A, 1B, and 1C described above is formed on the surface of the carbon-based material, so that ions of platinum group elements A plurality of coordination loci suitable for capturing are closely arranged. As a result, platinum group element ions can be more reliably retained on the surface of the carbon-based material.
  • the total atomic number ratio of nitrogen atoms and sulfur atoms to carbon atoms is preferably about 0.01 or more and about 0.1 or less.
  • the atomic ratio is based on values identified and quantified by X-ray photoelectron spectroscopy, as will be described later.
  • a polymer material containing a triazine ring is preferably used as the compound containing at least one of a nitrogen atom and a sulfur atom.
  • the polymer material containing a triazine ring is preferably supported on the surface of conductive carbon. Therefore, the carbon-based material contained in the metal-supported catalyst preferably contains a polymer material containing a triazine ring and conductive carbon that supports the polymer material on the surface.
  • the polymer material is preferably made of a polymer containing at least a triazine ring (C 3 N 3 ).
  • the polymer material is preferably composed of a covalently bonded organic structure containing a triazine ring.
  • a covalent organic structure is a molecule formed by connecting atoms such as hydrogen, carbon, nitrogen, oxygen, boron, and sulfur only by a covalent bond. More specifically, the covalent bond organic structure means a polymer having a structure in which a plurality of the same or different aromatic ring groups form a cyclic repeating unit by a covalent bond.
  • the covalently bonded organic structure also means a polymer having a two-dimensional or three-dimensional network structure in which the repeating unit is continuously connected to one or more other repeating units by a covalent bond.
  • Such a covalently bonded organic structure has a porous structure having meso and micro-sized pores, and has a low density and excellent thermal stability.
  • the polymer material used for the carbon-based material is preferably composed of a covalently bonded organic structure composed of repeating units having a plurality of triazine rings in the molecule.
  • a covalent organic structure can be formed by connecting such a repeating unit to another adjacent repeating unit by a covalent bond and repeating such a structure in a chain manner.
  • the polymer material is preferably composed of a covalent organic structure having a structure in which a plurality of triazine rings are connected via a covalent bond via an arylene, heteroarylene, or heteroatom.
  • arylene means a divalent functional group obtained by removing two hydrogen atoms bonded to a carbon atom constituting an aromatic ring from an aromatic hydrocarbon.
  • Heteroarylene means a divalent functional group formed by removing two hydrogen atoms from a heterocyclic compound having aromaticity.
  • the arylene is phenylene.
  • the heteroarylene is pyridylene.
  • the arylene and heteroarylene may have a substituent, and such a substituent is not particularly limited, and may be, for example, alkyl or halogen. Moreover, as a hetero atom, sulfur, boron, nitrogen, phosphorus, etc. can be mentioned, Preferably it is sulfur or nitrogen.
  • the polymer material used for the carbon-based material preferably has 1 nm to 50 nm pores.
  • the covalent bond organic structure preferably has pores of 1 nm to 50 nm.
  • the covalent bond organic structure preferably has a molecular weight in the range of 1000 to 20000.
  • the ion (cation) of the platinum group element can be coordinated to the polymer material.
  • the ions of the platinum group element form a coordinate bond with the heteroatom of the heteroaromatic ring that forms the covalent organic structure. It can exist in a complexed form with a binding organic structure.
  • the ion of a platinum group element coordinates to a covalent bond organic structure, the said ion can be disperse
  • the ion of the platinum group element can form a coordinate bond with an atom having an unshared electron pair contained in the polymer material. More preferably, the platinum group element ion can form a coordinate bond with the nitrogen atom contained in the polymer material. This makes it possible to efficiently disperse ions of the platinum group element in a monoatomic form.
  • a typical example of a covalently bonded organic structure used as a polymer material is a compound having a structure shown in FIG. 1A (a).
  • the compound shown in (a) of FIG. 1A can be synthesized by forming a triazine ring by condensation reaction of 2,6-dicyanopyridine and repeating the reaction, as shown in the Examples described later.
  • the compound has a structure in which triazine rings are linked by a covalent bond via a pyridylene group.
  • a repeating unit having a cyclic structure composed of three triazine rings and three pyridine rings is formed, and the plurality of repeating units are further linked by a pyridylene group.
  • the compound (a) in FIG. 1A is a polymer having a plurality of pores and a two-dimensional network structure.
  • the covalently bonded organic structure containing a triazine ring in FIG. 1A may be particularly referred to as a covalently bonded triazine structure (CTF, Covalent Triazine Framework).
  • metal ions can be supported. That is, a complex can be formed by forming a coordinate bond between the nitrogen atom of the triazine ring or the nitrogen atom of the pyridylene group and the metal ion. Further, like the covalently bonded organic structure of FIG. 1A, the polymer material containing a triazine ring contains a high concentration of atoms containing an unshared electron pair. The metal ions are stabilized by the interaction with the metal ions. Therefore, the polymer material containing a triazine ring can stably support metal particles having a small particle size.
  • the covalently bonded organic structure used as the polymer material is not limited to that shown in (a) of FIG. 1A, and (b) to (d) in FIG. 1A, (e) to (h) in FIG.
  • a compound containing a triazine ring such as 1C (i) can also be preferably used.
  • the polymer material may be a covalent organic structure in which one type of cyclic structure repeating unit is connected.
  • the polymer material may be a covalent organic structure as a copolymer in which a plurality of types of cyclic structure repeating units are linked.
  • the polymerization degree of the polymer material is preferably 10 or more, and more preferably 100 or more.
  • the degree of polymerization of the polymer material refers to the number average degree of polymerization.
  • a covalent organic structure having a triazine ring used as a polymer material can be obtained as follows. First, a triazine ring is formed by subjecting a monomer having a dicyano group or a tricyano group to a condensation reaction. Next, by repeating the condensation reaction, a covalent organic structure in which a plurality of triazine rings are finally connected by a covalent bond can be obtained.
  • the monomer having a dicyano group is preferably dicyanobenzene or dicyanopyridine.
  • the monomer having a tricyano group is preferably tricyanobenzene or tricyanopyridine.
  • the covalently bonded organic structure preferably has a structure in which a plurality of triazine rings are connected by covalent bonds via phenylene or pyridylene.
  • the covalent organic structure is preferably a compound obtained by a condensation reaction of dicyanobenzene or dicyanopyridine.
  • the monomer having a dicyano group can further have a substituent.
  • a substituent is not particularly limited as long as the condensation reaction of the cyano group proceeds, and can be, for example, an alkyl group or a halogen group.
  • conductive carbon carrying a polymer material on the surface is generally used as a conductive material for an electrode of a secondary battery.
  • the conductive carbon is capable of imparting electronic conductivity to the covalent organic structure by supporting the covalent organic structure used as a polymer material on the surface. preferable.
  • the conductive carbon is preferably a porous material from the viewpoint of more stably supporting the polymer material.
  • Examples of such conductive carbon include at least one selected from the group consisting of carbon black such as ketjen black and acetylene black, graphene, fine graphite particles, fullerene, carbon nanohorn, carbon paper, carbon cloth, and carbon felt. Can do.
  • As the conductive carbon amorphous carbon can also be used. Since these conductive carbons are excellent in conductivity and corrosion resistance, high electrode performance can be maintained over a long period of time.
  • the conductive carbon preferably has a large specific surface area in order to increase the amount of the polymer material supported.
  • the conductive carbon preferably has a specific surface area calculated by the BET method of 500 m 2 / g or more.
  • the shape of the conductive carbon is not particularly limited, and examples thereof include a spherical shape, a plate shape, a scale shape, a column shape, and a needle shape. Furthermore, the conductive carbon is preferably in the form of nanoparticles.
  • the average primary particle diameter of the conductive carbon is preferably 10 nm to 1000 nm, and more preferably 10 nm to 300 nm. When the particle diameter of the conductive carbon is within this range, the polymer material and the metal ions coordinated to the polymer material can be highly dispersed.
  • the particle diameter of conductive carbon can be calculated
  • SEM scanning electron microscope
  • TEM transmission electron microscope
  • the ratio of the covalent bond organic structure and the conductive carbon constituting the polymer material is preferably 100: 10 or more of the covalent bond organic structure: conductive carbon in terms of mass ratio. More preferably, the covalent bond organic structure: conductive carbon is 100: 20 to 100: 5000 by mass ratio.
  • the polymer material is preferably supported on the surface of the particulate conductive carbon.
  • the polymer material is composed of a covalent organic structure
  • the covalent organic structure is a material with low conductivity
  • the covalent organic structure is thin and easily undergoes electron transfer.
  • the film is supported on the surface of the conductive carbon by a film thickness. Since the covalent bond organic structure is supported in the form of a thin film, the distance between the covalent bond organic structure and the conductive carbon is reduced, and the distance between the covalent bond organic structure and the conductive carbon is reduced. Electron transfer becomes easy. As a result, the catalytic activity of the metal-supported catalyst can be further improved.
  • the polymer material may cover the entire surface of the conductive carbon, but the carbon-based material is not limited to such an embodiment.
  • the polymer material may be supported on a part of the surface of the conductive carbon.
  • the metal particles containing a platinum group atom are supported on the surface of a carbon-based material.
  • the metal particles supported on the surface of the carbon-based material are particles in a metal state in which platinum group atoms are assembled by metal bonds.
  • the platinum group atom includes at least one selected from the group consisting of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt).
  • the platinum group atom is preferably platinum (Pt).
  • the metal particles containing a platinum group atom preferably have a particle size of 0.5 nm or more and 15 nm or less. Here, the particle diameter is based on a value observed with a high-resolution transmission electron microscope (HR-TEM).
  • the metal particles containing platinum group atoms have a shape (w> h) in which the width w in the surface direction is larger than the height h. That is, the metal particles spread in the direction of the surface of the carbon-based material that carries the metal particles, and the direction perpendicular to the surface that carries the metal particles has a thin island structure.
  • the metal particles have an island-like structure, the proportion of platinum group atoms exposed on the surface increases, and the proportion of platinum group atoms having no catalytic action located inside the metal particles can be reduced. Therefore, a metal-supported catalyst in which the amount of platinum group element used is reduced while maintaining high catalytic activity can be realized.
  • the metal particles having such an island-like structure are caused by capturing the platinum group element on the surface of the carbon-based material by coordination of ions of the platinum group element. Specifically, when the ions of platinum group elements held by coordinate bonds with nitrogen atoms or sulfur atoms on the surface of the carbon-based material are reduced, the reduced platinum atoms aggregate together to form particles. However, since the platinum group elements immobilized on the surface of the carbonaceous material in advance move and aggregate on the surface of the carbonaceous material, the aggregated platinum group atoms can form the island-shaped structure described above.
  • the mass ratio of the platinum group atom in the metal particle to the carbon atom in the carbon-based material [mass of platinum group atom in the metal particle] ] / [Mass of carbon atoms in the carbon-based material]).
  • the projected area ratio of platinum group atoms to carbon atoms [projected area of platinum group atoms] / [projected area of carbon atoms]) in the image when the metal-supported catalyst is observed with a high-resolution transmission electron microscope is S Let R be.
  • the projected area ratio of the platinum group atom metal particles to the carbon-based material in the bright field image of the metal-supported catalyst observed with a high-resolution transmission electron microscope [projection area of the platinum group atom metal particles] / the projected area of the carbonaceous material]) and S R.
  • S R / W is 2.0 or more and 4.0 or less (2.0 ⁇ S R /W ⁇ 4.0).
  • S R / W is smaller than 1. That is, the projected area ratio is not so large with respect to the mass ratio. This indicates that the amount of platinum group element used is not significantly reduced.
  • S R / W is less than 2.0, platinum particles do not form an island structure.
  • S R / W is larger than 4.0, the metal lattice structure becomes irregular and the oxygen reduction activity decreases.
  • the high-resolution transmission electron microscope is a transmission electron microscope capable of observation at a magnification of 1 million times or more.
  • the quantification of carbon atoms and platinum group atoms in X-ray photoelectron spectroscopy can be performed as follows. First, for the peak derived from each atom, a baseline is drawn by the Shirley method for an average value between 2.0 eV from the low energy end of the peak to the smaller end. Similarly, a baseline is drawn by the Shirley method for an average value between 2.0 eV from the high energy end of the peak to the larger side. Then, the integrated intensity of the peak of each atom is obtained by integrating the absolute value of the difference between the baseline and the peak.
  • the mass of carbon atoms contained in the metal-supported catalyst and the platinum group are determined from the relationship between the integrated intensity of the peak of each atom and the relative sensitivity coefficient.
  • the atomic mass ratio can be determined.
  • the metal-supported catalyst having the above-described characteristics can be produced, for example, by coordinating a cation of a platinum group element to a carbon-based material and then reducing the cation of the platinum group element.
  • a carbon-based material containing at least one of a nitrogen atom and a sulfur atom is prepared.
  • Such a carbon-based material can be produced by the method described above.
  • platinum group element cations are coordinated to the carbon-based material.
  • a carbon-based material is added to an aqueous solution containing a platinum group element cation and stirred to coordinate the platinum group element cation to nitrogen and sulfur located on the surface of the carbon-based material.
  • the cation of a platinum group element is arrange
  • the reduction of the cation of the platinum group element can be performed by a method of firing a carbon-based material coordinated with ions in a reducing atmosphere or an inert atmosphere.
  • the reduction of the cation of the platinum group element can be performed by a method of applying a potential at which platinum (II) ions can be reduced to a carbon-based material coordinated with platinum (II) ions.
  • a trace amount of platinum group atoms can be arranged on the surface of the carbon-based material. Further, during reduction, platinum group atoms can be moved at the atomic level by migration on the surface of the carbon-based material. Therefore, the metal particle formed by aggregation of platinum group atoms can exhibit a highly anisotropic shape.
  • the metal-supported catalyst of the present disclosure has various catalytic actions exhibited by platinum group elements.
  • the metal particles when the metal particles have an island-like structure, the relative proportion of the (111) plane and the (100) plane with relatively high oxygen reduction activity increases. For this reason, the metal-supported catalyst of the present disclosure exhibits particularly high oxygen reduction activity.
  • the metal-supported catalyst of the present disclosure is suitably used as a catalyst in the following reaction, for example.
  • the oxygen reduction reaction shown below is a cathode reaction in H 2 / O 2 fuel cells, salt electrolysis, etc., and is important in energy conversion electrochemical devices and the like.
  • a hydrogen generation reaction that is a reaction that is a pair of hydrogen oxidation reactions is important as a reaction at a hydrogen generation electrode for water electrolysis hydrogen generation.
  • the metal-supported catalyst of the present disclosure can be suitably used as a catalyst for these reactions. Therefore, it is considered that an expanding demand can be satisfied while reducing the amount of platinum group element used as a catalyst of an energy source that is considered to be widely used in the future.
  • FIG. 2 shows an example of the configuration of the fuel cell according to the present disclosure.
  • a load 14 to which current is supplied when connected to the fuel cell is also illustrated.
  • the fuel cell 10 is a primary cell capable of discharging electricity.
  • a hydrogen fuel cell such as a polymer electrolyte fuel cell (PEFC) and a phosphoric acid fuel cell (PAFC), and a microbial fuel cell ( MFC).
  • PEFC polymer electrolyte fuel cell
  • PAFC phosphoric acid fuel cell
  • MFC microbial fuel cell
  • a hydrogen fuel cell is a fuel cell that obtains electrical energy from hydrogen and oxygen by the reverse reaction of water electrolysis.
  • PEFC, PAFC, alkaline fuel cell (AFC), molten carbonate fuel cell (MCFC), solid An electrolyte fuel cell (SOFC) or the like is known.
  • the fuel cell 10 is preferably PEFC or PAFC.
  • PEFC is a fuel cell using a proton conductive ion exchange membrane as an electrolyte material
  • PAFC is a fuel cell using phosphoric acid (H 3 PO 4 ) impregnated in a matrix layer as an electrolyte material.
  • Such a fuel cell 10 includes, for example, an electrolyte solution 11 (electrolyte material) as shown in FIG.
  • the fuel cell 10 includes an anode 12 (fuel electrode) and a cathode 13 (air electrode).
  • the anode 12 is an electrode that emits electrons to the load 14 by an oxygen generation reaction.
  • the cathode 13 is an electrode through which electrons flow from the load 14 due to an oxygen reduction reaction.
  • the cathode 13 is configured as a gas diffusion electrode and includes the above-described metal-supported catalyst.
  • the gas diffusion electrode can be suitably applied to electrodes such as hydrogen fuel cells and MFCs.
  • the fuel cell 10 according to the present disclosure may have a known configuration except that the fuel cell 10 includes a cathode 13 and the cathode 13 is a gas diffusion electrode including a metal-supported catalyst.
  • the cathode 13 is configured as a gas diffusion electrode and includes a metal-supported catalyst.
  • the present invention is not limited to such a configuration.
  • an electrode including a metal-supported catalyst can be used for both the anode 12 and the cathode 13.
  • a gas diffusion electrode including a metal-supported catalyst may be used as the anode 12.
  • the metal-supported catalyst contained in the anode 12 promotes an oxidation reaction (H 2 ⁇ 2H + + 2e ⁇ ) of hydrogen gas as a fuel, and donates electrons to the anode 12.
  • a gas diffusion electrode provided with a metal-supported catalyst may be used as the cathode 13.
  • the metal-supported catalyst contained in the cathode 13 promotes a reduction reaction (1 / 2O 2 + 2H + + 2e ⁇ ⁇ H 2 O) of oxygen gas that is an oxidant.
  • the gas diffusion electrode including the metal-supported catalyst is mainly used as a cathode that causes the same electrode reaction as that of the hydrogen fuel cell.
  • the metal-supported catalyst can be suitably used for an electrode of a fuel cell.
  • the use of the metal-supported catalyst is not limited to the fuel cell, and may be used as an electrode of various electrochemical devices.
  • electrochemical devices include water electrolyzers, carbon dioxide permeators, salt electrolyzers, metal-air batteries (such as lithium-air batteries).
  • a metal-supported catalyst was produced by adsorbing platinum (II) ions on a carbon-based material and calcining the carbon-based material on which the platinum (II) ions were adsorbed in a reducing atmosphere or an inert atmosphere.
  • FIG. 3 shows an observation image of the metal-supported catalyst of this example. As shown in FIG. 3, in the metal-supported catalyst 1 of this example, it can be seen that metal particles 2 made of platinum are supported on the surface of a porous carbon-based material 3. Then, from FIG.
  • XPS X-ray photoelectron spectroscopy
  • Example 2 Platinum (II) ions are adsorbed on a carbon-based material, and platinum (II) ions are reduced by applying a potential at which platinum (II) ions can be reduced to carbon-based materials on which platinum (II) ions are adsorbed.
  • a supported catalyst was prepared.
  • a nitrogen-containing carbon-based material carrying platinum chloride ions was obtained by the same method as in Example 1.
  • 100 mg of the nitrogen-containing carbon-based material was dispersed ultrasonically in a mixture of 0.95 mL of Nafion and 3.2 mL of ethanol. And the obtained dispersion liquid was apply
  • the glassy carbon coated with the nitrogen-containing carbon-based material described above was -0.1 Vvs. In 0.1 M perchloric acid aqueous solution. An RHE potential was applied for 10 hours. Then, it wash
  • FIG. 4 shows an observation image of the metal-supported catalyst of this example.
  • the metal-supported catalyst 1 of this example also has metal particles 2 made of platinum supported on the surface of a porous carbon-based material 3.
  • the ratio (S R ) of the projected area of the darkly observed region derived from the metal particles to the projected area of the carbon-based material was obtained. .
  • S R was 0.041.
  • Comparative Example 1 A commercially available 60 wt% platinum-supported carbon material (HiSPEC (registered trademark) 9100, manufactured by Johnson Matthey) was used as the metal-supported catalyst of Comparative Example 1.
  • FIG. 5 shows an observation image of the catalyst of this example using a transmission electron microscope. As shown in FIG. 5, it can be seen that the catalyst of Comparative Example 1 has a large amount of platinum 4 supported on carbon black 5.
  • Comparative Example 2 A commercially available 40 wt% platinum-supported carbon-based material (manufactured by Johnson Matthey, HiSPEC 4000) was used as the metal-supported catalyst of Comparative Example 2.
  • FIG. 6 shows an observation image of the catalyst of this example using a transmission electron microscope. As shown in FIG. 6, it can be seen that the catalyst of Comparative Example 2 also has a large amount of platinum 4 supported on carbon black 5 in the same manner as the catalyst of Comparative Example 1.
  • Table 1 summarizes the mass ratio (W) of metal atoms to carbon atoms, the projected area ratio of metal atoms to carbon atoms (S R ), S R / W, and the surface exposure rate in each example.
  • the ratio (S R ) of the projected area in the transmission electron microscope image is different by about one digit between Example 1 and Example 2, and Comparative Example 1 and Comparative Example 2.
  • the composition ratio (W) by X-ray photoelectron spectroscopy is generally It can be seen that this corresponds to the mass ratio.
  • the ratio of platinum to the carbon-based material in the metal-supported catalysts of Example 1 and Example 2 is about 1 wt%, compared with the commercially available platinum catalyst used in Comparative Example 1 and Comparative Example 2, It can be seen that the amount of platinum used is several tenths or less. Then, considering that the atomic weight of platinum is 10 times or more that of carbon, it can be seen that in Example 1 and Example 2, the supported platinum particles are very small compared to the carbon-based material.
  • S R / W of Comparative Example 1 and Comparative Example 2 is smaller by one digit or more. That is, it can be seen that the conventional platinum-supporting carbon-based material does not satisfy the condition of 2.0 ⁇ S R /W ⁇ 4.0.
  • Example 1 and Example 2 exceeds 30%, and it can be seen that the metal-supported catalyst of the present disclosure has a structure that does not match the “uniform sphere model”.
  • the metal-supported catalyst of the present disclosure is suitably used as a catalyst for various chemical reactions using a platinum group element as a catalyst.
  • it is suitably used as a catalyst for oxygen reduction reaction, hydrogen oxidation reaction, hydrogen generation reaction, etc. in fuel cells, hydrogen generators and the like.

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Abstract

L'invention concerne un catalyseur sur support métal (1) comprenant des atomes de métal du groupe du platine et des atomes de carbone. Si W est le rapport de masse des atomes de métal du groupe du platine aux atomes de carbone tels que mesurés par spectroscopie photoélectronique à rayons X et si SR est le rapport de surface projetée pour les atomes de métal du groupe du platine aux atomes de carbone dans une image observée par un microscope électronique à transmission à haute résolution pour le catalyseur sur support métal, alors le rapport SR/W est de 2,0 à 4,0. Ainsi, le catalyseur sur support métal peut présenter une activité catalytique élevée même si la proportion de l'élément du groupe du platine est faible.
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JP2023144295A (ja) * 2022-03-28 2023-10-11 トヨタ自動車株式会社 電気化学的酸素還元触媒
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Cited By (4)

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Publication number Priority date Publication date Assignee Title
JP2020040857A (ja) * 2018-09-12 2020-03-19 星和電機株式会社 共有結合性有機構造体の焼成体およびその製造方法
US12489121B2 (en) 2020-09-10 2025-12-02 Nisshinbo Holdings Inc. Metal-loaded catalyst, battery electrode and battery
CN113549956A (zh) * 2021-07-02 2021-10-26 北京化工大学 一种低载量铂催化气体扩散电极及其制备方法和应用
JP2023144295A (ja) * 2022-03-28 2023-10-11 トヨタ自動車株式会社 電気化学的酸素還元触媒

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